My recent forays into freezer-bag cooking have yielded mixed results.
This summer in the ADK's it worked great for two of us. I made a double-thickness fleece cozy and boiled water with a Caldera Cone. Temperatures never went below 50 F.
Last week at the Grand Canyon things did not go so well. Temperatures were usually in the mid-30's at dinner time. I used a cozy made out of 1.1 oz nylon and 5 oz Climashield, about the same thickness as the fleece cozy but one half the weight.
The problem was that although the food rehydrated, by the time it was ready, 5 mins or sometimes a few mins more, it was only luke-warm.
I first thought the cozy was too thin, but then I noticed that just after pouring (say) 2 cups of boiling water into the bag, it was already sort of cool. That is, the ingredients were cold enough that much of the heat from the hot water was lost right at the start.
This was especially true if one of the ingredients was something that had been rehydrating all day long, e.g something that had 3/4 cup of cold water already in it.
How do you avoid such problems? Was my cozy not good enough? Or is there a lower temperature limit to freezer-bag cooking.